Warfarin Bridging Protocol for Surgery
For patients requiring temporary interruption of warfarin therapy for surgery, a standardized bridging protocol based on thromboembolic risk assessment should be implemented, with warfarin discontinued 5 days before surgery and bridging anticoagulation with LMWH for high-risk patients only.
Risk Assessment for Bridging
The decision to use bridging anticoagulation depends on balancing the risk of thromboembolism versus bleeding:
High Thromboembolic Risk (Consider Bridging)
- Recent VTE within 3 months 1
- Active cancer with VTE 1
- Mechanical heart valves 1
- Atrial fibrillation with high CHADS2 score 1
- Antiphospholipid syndrome with recurrent thrombosis 1
Low Thromboembolic Risk (No Bridging Needed)
Standard Bridging Protocol
Pre-Procedure Management
- Stop warfarin 5 days before surgery 1, 2
- Check INR the day before surgery; proceed if INR ≤1.5 1
- If INR >1.5 and ≤1.8 day before surgery, consider low-dose oral vitamin K (1-2.5 mg) 1
Bridging with LMWH (For High-Risk Patients Only)
- Start LMWH when INR falls below 2.0, typically 3 days before surgery 1
- Use therapeutic dose LMWH (e.g., enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily) 1
- Administer last pre-operative LMWH dose 24 hours before surgery at half the total daily dose 1
- For high bleeding risk procedures, consider intermediate-dose LMWH regimens 1
Post-Procedure Management
- Resume warfarin 12-24 hours after surgery (evening of or next morning) when hemostasis is adequate 1
- For low bleeding risk procedures:
- For high bleeding risk procedures:
Special Considerations
Minor Procedures
- For minor dental procedures, consider continuing warfarin with oral prohemostatic agents 1
- For minor dermatologic procedures and cataract surgery, continuing warfarin is often appropriate 1
Monitoring
- Check INR before surgery to ensure it's ≤1.5 1, 2
- Monitor INR 4-5 days after resuming warfarin 1
- Continue LMWH until INR reaches ≥2.0 1
Potential Complications and Cautions
- Residual anticoagulant effect may persist if LMWH is given too close to surgery, especially with therapeutic doses 3, 4
- Higher BMI and shorter interval since last LMWH dose are associated with higher pre-operative anti-Xa levels 3
- Major bleeding risk increases with therapeutic-dose LMWH, particularly when resumed too soon after high bleeding risk procedures 1
- If possible, delay elective procedures until at least 3 months after acute VTE 1
Evidence Quality Considerations
- Most recommendations are based on observational studies rather than randomized trials 1
- Standardized bridging protocols have demonstrated low rates of thromboembolism (0.4-0.5%) and major bleeding (0.7-1.2%) 5, 6
- Half-therapeutic dose LMWH regimens may provide adequate protection with lower bleeding risk in intermediate-risk patients 6